The present invention relates to the art of induction heating and, in particular, an apparatus and method for heat treating and inspecting camshafts for internal combustion engines.
The present invention finds particular utility in the heat treatment of internal combustion camshafts and will be described with particular reference thereto; however, it will become hereinafter apparent that the invention has broader applications for the heat treating of cylindrical shafts having a plurality of axially spaced areas to be heat treated wherein the apparatus must be capable of processing a number of shaft designs without a changeover operation for each design.
The camshafts for internal combustion engines are typically elongated cylindrical shafts having a plurality of cam lobes or eccentrics formed thereon which coact with the valve train to open and close associated intake or exhaust valves of the engine. The number of cam lobes, the lobe size, the spacing thereof and the length of the camshaft vary from engine to engine. Because of the demanding service requirements, the cam lobes must be wear resistant and durable. Accordingly, the cam surfaces are hardened preferably by induction heating followed by liquid media quenching. Under current practice, each camshaft design or configuration requires a separate heat treating apparatus or conversion of a somewhat common apparatus. Such conversion must account for length, cam spacing, cam size, number of cams, inductive power level and heating time, quenching time and quenching media. Consequently, the conversion is costly and time consuming. Moreover, such systems require a substantial inventory of unprocessed camshafts to provide an economical production run.